> For the complete documentation index, see [llms.txt](https://docs.console.zenlayer.com/welcome/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.console.zenlayer.com/welcome/cloud-networking/overview/concepts.md).

# Concepts

## Cloud Networking

Cloud Networking focuses on serving your "data exchange": over a single global backbone (Fabric), it connects multiple access points using a Layer 2 network or a Layer 3 network.

Let's take a closer look at the product:

* Access Point — an endpoint of a connection, representing one party's resources in the interconnection (a data center, a public cloud, an elastic compute instance, and so on).
* A connection = the backbone (handles long-distance transport) + two or more access points (the resources you want to link).
* What you do on zenConsole is choose the connection type (Layer 2 / Layer 3), then add the access points you want to link.

## Access Points and Their Types

Every "party" of resources you want to link is an access point. Cloud Networking supports the following access point types:

### Data Center (Port)

A Port is the physical access point of a device in a backbone POP (Point of Presence) — the basic socket for data center access. A data center connects to a port physically through a Cross Connect: a physical point-to-point direct cable within the data center, best when your facility and the port are in the same or a very close facility.

### Public Cloud <a href="#cloud-connect" id="cloud-connect"></a>

Connect through the pre-built Cloud Connect between Zenlayer and major cloud providers — no need to set up a physical dedicated line with the cloud provider yourself. Currently supported: AWS, Tencent Cloud, Google Cloud, Alibaba Cloud, and Microsoft Azure (more to come).

### Partner

Connect to the backbone through a Zenlayer partner's network node, used to cover locations or resources that Zenlayer's own POPs don't reach directly but a partner can.

### Elastic Compute

Through the Border Gateway network node, connect elastic compute resources in a global VPC to a Layer 3 network, interconnecting with your other access points such as data centers and public clouds.

### Bare Metal

Add an existing bare metal Virtual Private Cloud (VPC) as an access point, so resources inside the VPC interconnect with infrastructure in your data centers or public clouds.

{% hint style="info" %} <mark style="color:blue;">Note</mark>

<mark style="color:blue;">A VPC contains subnets; subnets with the same IP range cannot communicate. Plan your subnet IP ranges in advance to avoid connection issues.</mark>
{% endhint %}

### Edge Gateway (Virtual Edge) <a href="#virtual-edge" id="virtual-edge"></a>

Traditional BGP/MPLS IP VPN requires deploying a CE (customer edge) device per VPN — costly and complex to deploy. The Edge Gateway instead connects quickly by establishing an IPsec (Internet Protocol Security) tunnel from your office to the backbone, isolated and secure. Best when you need Layer 3 connectivity and your office is far from the POP port or has smaller bandwidth needs.

### Access Point Types at a Glance

| Access Point Type | Representative Resources                                             | Access Method        |
| ----------------- | -------------------------------------------------------------------- | -------------------- |
| Data Center       | Owned / colocated IDC                                                | Port + Cross Connect |
| Public Cloud      | AWS / Tencent Cloud / Google Cloud / Alibaba Cloud / Microsoft Azure | Cloud Connect        |
| Partner           | Resources reachable via partner networks                             | Partner node         |
| Elastic Compute   | Elastic compute in a global VPC                                      | Border Gateway       |
| Bare Metal        | Bare metal VPC                                                       | Direct VPC access    |
| Edge Gateway      | Office / remote site                                                 | IPsec tunnel         |

## Backbone (Fabric)

The backbone is the "high-speed trunk in the middle" connecting all access points — Zenlayer's global SDN private network, the foundation for long-distance data transport. It bypasses public internet congestion and delivers low-latency, low-loss, and predictable transmission quality. On top of the backbone, two connection types are offered: Layer 2 and Layer 3 networks.

### Layer 2 Network <a href="#private-connect" id="private-connect"></a>

A Layer 2 (data link layer) connection over the SDN backbone, formed by two endpoint nodes over a leased line. It uses a WAN protocol to encapsulate local network traffic into frames for transport — simple to configure and point-to-point transparent, ideal for direct two-point links.

### Layer 3 Network <a href="#cloud-router" id="cloud-router"></a>

A Layer 3 connection over the SDN backbone, which can consist of multiple endpoint nodes (typically 2–10 access points). It groups and routes traffic from dozens or even hundreds of physical LAN segments, supporting complex multi-point and multi-cloud networking, and interconnects via BGP or static routing.